Polymethylmethacrylate (PMMA), as a synthetic resin using an MMA monomer as a main material, has excellent transparency, compared to other plastics. In addition, PMMA has superior scratch resistance due to high surface hardness. Further, PMMA has excellent chemical resistance, surface gloss, and adhesion, as well as excellent weather resistance. Due to the aforementioned properties, PMMA is broadly used in materials of automobiles and electrical and electronic components. However, due to poor impact resistance of PMMA, the thicknesses of products to which PMMA is applied are increased or the products are limitedly used. So as to improve such low impact resistance of PMMA resin, a method of modifying a PMMA resin with an acrylonitrile-butadiene-styrene (ABS) resin is used. However, this method has a disadvantage of poor weather resistance by a double bond of butadiene. Accordingly, PMMA resin is modified with acrylonitrile-styrene-butyl acrylate (ASA) and a silicon-based impact modifier, instead of ABS resin, whereby impact resistance is improved. However, in the case of PMMA resin modified like this, scratch resistance, gloss, and transparency are decreased, compared to conventional PMMA resin (related prior document: Korean Laid-Open Publication No. 2002-0022351).